Where you see "yes" in the column called "Reverse" it means that the formula given here is reversed for night-time charts, i.e. those having the sun below the horizon line of the Ascendant/Descendant. For example, in a night-time chart the formula for the Part of Wisdom becomes ASC + Saturn - Sun.

Traditionally, the formulae which are reversed are those that use either the Sun or the Moon in their calculation. This is because the Sun rules the day and the Moon rules the night. However, some modern parts do not adhere to this.